AQA GCSE Chemistry Key Words

Key Chemical Terms

• Acid: Low pH solution rich in hydrogen ions.
• Activation Energy: Minimum energy required to initiate a chemical reaction.
• Alkali: High pH solution containing hydroxide ions.
• Alkali Metals: Highly reactive metals located on the left of the periodic table.
• Alkanes: Hydrocarbons characterized by single bonds.
• Alkenes: Hydrocarbons with at least one double bond.
• Alloy: A mixture of metals that creates distorted atomic layers, preventing sliding.
• Anode: The positive electrode during electrolysis.
• Aqueous Solution: A solution that dissolves a substance in water.
• Atom: The basic unit of matter, composed of protons, neutrons, and electrons.
• Atomic Number: Represents the number of protons in an atom.
• Base: Metal oxides, hydroxides, or carbonates that react with acids to form salt.
• Biodegradable: Materials able to decompose through microbial action.
• Biofuel: Fuels produced from biological materials such as plants and animals.
• Bioleaching: Using bacteria to extract metals from low-grade ores.
• Blast Furnace: Industrial apparatus used to extract iron from its ore via complex chemical reactions.
• Bromine Water: Test agent (orange liquid) for detecting double bonds in organic compounds.
• Burette: Long glass tube with a tap for measuring liquid volumes.
• Carbon Footprint: Quantifies carbon emissions from everyday activities.
• Catalyst: A substance that accelerates a reaction without being consumed.
• Cathode: The negative electrode in electrolysis.
• Chromatography: Technique for separating dissolved substances via solvent movement on a medium.
• Collision Theory: Explains reactions as collisions between particles with adequate energy.
• Combustion: The process of burning a substance in the presence of oxygen.
• Compound: A substance formed from two or more chemically bonded elements.
• Covalent Bonding: The sharing of electron pairs between non-metals.
• Cracking: Process of breaking down long hydrocarbon chains into shorter chains.
• Crude Oil: Naturally occurring mixture of various-length hydrocarbons from decomposed organic matter.
• Desalination: The process of removing salt from water.
• Delocalised Electron: Electrons that are not tied to a single atom but are spread out across several atoms.
• Dependent Variable: The variable measured in response to changes in the independent variable.
• Diamond: A form of carbon with a tetrahedral lattice structure and four covalent bonds to each carbon atom.
• Diffusion: The spontaneous mixing of molecules due to random particle movement.
• Displacement Reaction: One element replaces another in a compound.
• Distillation: Method to separate liquids based on boiling points via evaporation and condensation.
• Electrolysis: The process of using electricity to separate compounds.
• Electrolyte: A conductive liquid containing free ions used in electrolysis.
• Electron: A negatively charged subatomic particle found in atomic shells, effectively massless.
• Element: A basic substance made up of atoms with identical properties, found on the periodic table.
• Endothermic Reaction: A chemical reaction that absorbs energy from its surroundings.
• Equilibrium: The state in a reversible reaction where the forward and reverse reaction rates are equal.
• Exothermic Reaction: A reaction that releases energy, typically as heat or light.
• Fermentation: Biochemical process converting glucose to ethanol and carbon dioxide by yeast enzymes.
• Filtration: A physical separation technique to distinguish soluble and insoluble substances based on solubility.
• Flammability: The likelihood of a substance igniting in the presence of fire.
• Formulation: Specific combinations of different compounds designed for particular purposes.
• Fractional Distillation: Technique for separating components of a mixture based on differing boiling points.
• Gas: A state of matter where particles move freely and can be compressed.
• Graphite: A form of carbon where each atom forms three bonds, resulting in layers that can slide.
• Greenhouse Gas: Gases that trap heat (infrared radiation) in Earth's atmosphere.
• Halogen: Highly reactive non-metals situated on the periodic table's right side.
• Homologous Series: Groups of organic compounds with the same functional group and similar chemical properties.
• Hydrocarbon: Compounds solely composed of carbon and hydrogen.
• Incomplete Combustion: Occurs in insufficient oxygen, producing carbon monoxide, a toxic byproduct.
• Intermolecular Forces: Attractive forces between molecules in a covalently bonded substance.
• Ion: An atom that has gained or lost electrons, carrying a charge.
• Ionic Bonding: The transfer of electrons from metals to non-metals, resulting in charged ions.
• Isotope: Variants of elements with the same number of protons but differing numbers of neutrons.
• Law of Conservation of Energy: States that mass in a reaction remains constant; mass of products equals mass of reactants.
• Life Cycle Assessment: An evaluation of environmental impacts of a product throughout its lifecycle.
• Liquid: A state of matter where particles can move, flow, and are incompressible.
• Mass Number: Total count of protons and neutrons in the nucleus of an atom.
• Melting Point: Temperature at which a solid transforms into a liquid.
• Metal: Elements on the left side of the periodic table that typically lose electrons to form positive ions.
• Mixture: A combination of different substances where each retains its own properties.
• Mole: The quantity of substance equal to its molecular mass in grams.
• Molecular Formula: Representation of the number and types of atoms in a molecule.
• Monomers: Small, reactive molecules that join in sequences to form polymers.
• Neutralisation: The reaction between an acid and an alkali producing a neutral solution (pH 7).
• Neutron: Neutral particle located in an atom's nucleus, contributing to mass.
• Noble Gas: Inert gases found on the right side of the periodic table, known for their lack of reactivity.
• Non-metal: Elements on the right side of the periodic table that typically gain electrons to form negative ions.
• Nucleus: Central part of the atom containing protons and neutrons.
• Orders of Magnitude: Comparisons of the scale or size of different values.
• Ore: Rock containing a significant amount of metal, making extraction economically viable.
• Oxidation: The process of losing electrons.
• Percentage Yield: A metric to express the efficiency of a reaction in terms of product yield.
• Periodic Table: A systematic arrangement of all known chemical elements.
• pH: A scale measuring how acidic or alkaline a solution is.
• Phytomining: Technique for extracting metals from low-grade ores using plants.
• Pipette: A laboratory tool used for measuring and transferring precise liquid volumes.
• Polymer: Large molecules formed from many repeating smaller units (monomers).
• Potable Water: Water deemed safe and suitable for drinking.
• Product: Material produced as a result of a chemical reaction.
• Reactant: Substance that undergoes a chemical change during a reaction.
• Reactivity Series: An ordered list of metals based on their reactivity.
• Reduction: The process of gaining electrons.
• Reversible Reaction: A reaction that can proceed in both forward and backward directions.
• Solid: A state of matter with fixed structure; particles vibrate around a fixed point.
• Titration: A method to determine the concentration of a solution through controlled addition of a titrant.
• Transition Metal: Elements in the middle of the periodic table; known for colored compounds and catalytic properties.
• Viscosity: A measure of a fluid's resistance to flow.

This quiz covers essential key terms for AQA GCSE Chemistry, helping students reinforce their understanding of core concepts. Familiarize yourself with terms like acid, alkali, and activation energy to excel in your studies and examinations.